1. Field of the Invention
Embodiments of the present invention are generally directed to insulated concrete composite wall panels. More specifically, embodiments of the present invention are directed to shear connectors for connecting inner and outer concrete layers of insulated concrete composite wall panels.
2. Description of the Related Art
Insulated concrete wall panels are well known in the construction industry. In general, such insulated panels are comprised of two layers of concrete, including an inner layer and an outer layer, with a layer of insulation sandwiched between the concrete layers. In certain instances, to facilitate the connection of the inner concrete layer and the outer concrete layer, the concrete layers may be tied together with one or more shear connectors to form an insulated concrete composite wall panel (“composite panel”). The building loads typically resolved by a composite insulated wall panel are wind loads, dead loads, live loads, and seismic loads. The shear connectors are, thus, configured to provide a mechanism to transfer such loads, which are resolved by the shear connectors as shear loads, tension/compression loads, and/or bending moments. These loads act can alone, or in combination. Tension loads are known to cause delamination of the concrete layers from the insulation layer. The use of shear connectors in concrete wall panels, thus, transfer shear and tension/compression loads so as to provide for composite action of the concrete wall panels, whereby both layers of concrete work together as tension and compression members.
Previously, shear connectors have been designed in a variety of structures and formed from various materials. For instance, previously-used shear connectors were often made from steel. More recently, shear connectors have been made from glass or carbon fiber and epoxy resins. The use of these newer materials increases the overall thermal efficiency of the composite panel by allowing less thermal transfer between the inner and outer concrete layers.
The continuing evolution of building energy codes has required buildings to be more efficient, including thermally efficient. To meet new thermal efficiency requirements in concrete wall panels, the construction industry has begun using thicker layers of insulation (and thinner layers of concrete) and/or more thermally efficient insulation within the panels. However, reducing the amount of concrete used in the panels will generally educe the strength of the panels. As such, there is a need for a shear connector for composite panels that provides increased thermal efficiency, while simultaneously providing increased strength and durability of the composite panels. There is also a need for lighter-weight composite panels that can be easily transported, oriented, and installed.